Berlin 2015 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 100: ZnO and its relatives
HL 100.4: Vortrag
Freitag, 20. März 2015, 10:15–10:30, EW 203
Influence of mechanical destruction on phonons and excitonic transition on polar and non-polar ZnO crystals — •Nadja Jankowski1, Christian Nenstiel1, Mark Berkahn2, Matthew Phillips2, and Axel Hoffmann1 — 1Institut für Festkörperphysik, Technische Universität Berlin, Berlin, Germany — 2School of Physics and Advanced Materials, University of Technology, Sydney, Australia
As Zinc Oxide (ZnO) is a very soft material it is very sensitive towards destruction during handling, thus it is interesting to study the influence of mechanical destruction on optical and structural properties. Therefore polar (c-orientated) and non-polar (a- and m-orientated) ZnO crystals where locally destroyed with a spherical indenter with a diameter of 1 µm and an applied load of 100 mN.
The influence of the destructed area on strain fields and crystal quality was investigated in detail by the means of Raman map scans. The shift of the E2high-mode revealed complex strain fields with hexagonally arranged strain fields for the polar plane and elongated V-shaped bands of strain for the non-polar plains.
The influence on the excitonic recombination due to destruction was investigated by micro photoluminescence at about 10 K. In general the excitonic transition shows a shift according to the strain fields. On the non-polar planes a change of the intensity ratio between high and low energy neutral bound excitons and the ionized bound ones can be observed in the compressive and tensile strained regions. Therefore a clear connection between the change of excitonic transition and the indentation induced strain fields can be observed.